For more than two decades, the oil market hung to Ali al-Naimi’s every word -- whether he was taking a characteristic stroll at dawn on Vienna’s Ringstrasse, hurrying through a hotel lobby after a conference, or dodging throngs of reporters at an OPEC meeting.

Now that he’s done with his near 21-year stint as Saudi Arabia’s oil minister, during which his utterances could move everything from crude to currencies and stocks worldwide, al-Naimi says he doesn’t want to talk about the market anymore.

"As far as oil prices and oil, I have left that behind,” he said on Friday at an event in Singapore to launch his book ‘Out of the Desert: My Journey From Nomadic Bedouin to the Heart of Global Oil’.

Al-Naimi was the architect of the 2014 strategy by the Organization of Petroleum Exporting Countries to continue pumping amid a global glut to squeeze out higher-cost producers including U.S. shale drillers. After becoming oil minister in 1995, he steered the world’s largest crude exporter through wild price swings, regional wars, technological progress and the rise of climate change as a key policy concern. He stepped down from the role last year.

He’s not easing up and relaxing into retirement though. Instead, he’s looking up to the sun after years of musing about what’s pumped from under the ground. “Now I’m much more interested in solar energy, making solar panels,” he said. “If you could help me there, good.”

Saudi Arabia is embarking on a $50 billion renewable-resources push to meeting growing energy demand while tempering domestic oil use. Starting this year, the OPEC’s biggest crude producer plans to develop almost 10 gigawatts of renewable energy such as solar and wind power by 2023.

Staying youngAl-Naimi’s focus on solar energy is his way of staying young. “Otherwise you’ll die. You need to keep the brain going,” said the 81-year-old, who still goes running and mountain climbing to stay fit.

The title of his book refers to his childhood days as part of his mother’s nomadic tribe, when he used to take care of lambs. His life made a decisive turn in early adolescence when he took over a job as an office boy for Arabian American Oil Co., the forerunner of state-run Saudi Aramco, after the death of an older brother. He went on to study at Lehigh University and Stanford University, rose through the ranks at Aramco, and the government selected him to lead the oil ministry in August 1995.

Al-Naimi’s successor, Khalid Al-Falih, has marshaled a different oil-market strategy. OPEC and some other producers including Russia started cutting output last month as part of a deal aimed at easing bloated global inventories, with Saudi Arabia making significant curbs to its production. But that’s also prompted a resurgence in U.S. drilling and an increase in the flow of crude from rivals to the group’s prized Asian market.

Brent crude, the benchmark for more than half the world’s oil, traded 0.5 percent higher at $56.24 a barrel on the ICE Futures Europe exchange by 4:11 p.m. London time. Prices were at more than $115 a barrel in mid-2014.

In his book, al-Naimi strongly defended the no-limits approach he convinced OPEC to adopt. The best way to re-balance the market is still to let supply, demand and prices work, he wrote.

At Friday’s event in Singapore, when asked about his views on OPEC complying with the deal to cut output and whether Russia would keep its promise of reducing production, he stopped and thought for a moment. Then he said sorry and left the venue without commenting.